Potential and Main Technological Challenges for Material and Energy Recovery From Fine Fractions of Landfill Mining: A Critical Review

Abstract

Multiple landfill mining investigations of municipal solid waste landfills have been carried out worldwide in the past decades. Some of these studies have led to the conclusion that landfill mining is not feasible and could represent more of a problem than a solution for old landfill sites. This is the case to a certain extent because, to this day, material and energy recovery in landfill mining has been restricted to the coarse fractions (>10 mm to >60 mm) in most projects, while the fine fractions (<10 mm to <60 mm) have been often redirected to the landfill with poor or no treatment at all despite their recovery potential. The fine fractions account for 40-80 wt.% of the total amount of the landfill-mined material. Its material composition is characterized by about 40-80 wt.% decomposed organic matter or weathered mineral fractions which cannot be hand-sorted, followed by significant amounts of calorific fractions and a small amount of metals. The main chemical compound found in landfill mining fine fractions is SiO 2 , mostly present as quartz and minor amounts of sheet silicates, followed by CaO, mostly present in carbonate minerals. MgO, Fe 2 O 3 and Al 2 O 3 represent minor components. Heavy metals are present in concentrations of few to several hundreds of mg/kg without a clear general trend of enrichment compared to the coarse fractions. In contrast, the net calorific value of the fine fractions (about 3-9 MJ/kg DM) can be several times lower than that of the coarse fractions (about 10-30 MJ/kg DM). These data clearly indicate that both a mineral fraction for waste-to-material and a calorific fraction for waste-to-energy might be recovered if suitable mechanical processing technologies can be employed. The potential of the fine fractions for material and energy recovery, as well as the main technological challenges to unlock it, are the main topics discussed in the present review article. This article has been elaborated within the framework of the EU Training Network for Resource Recovery through Enhanced Landfill Mining-NEW-MINE.

CASE STUDY ON ENHANCED LANDFILL MINING AT MONT-SAINT-GUIBERT LANDFILL IN BELGIUM: MECHANICAL PROCESSING, PHYSICO-CHEMICAL AND MINERALOGICAL CHARACTERIZATION OF FINE FRACTIONS <4.5 MM

“…Fine fractions produced by mechanical processing of landfill mining materials are a major obstacle for an economically feasible (enhanced) landfill mining ((E)LFM) due to the predominant amounts and problematic characteristics (García López, et al, 2019;Hernández Parrodi, et al, 2019b;Hernández Parrodi, Höllen, & Pomberger, 2018a;Hernández Parrodi, Höllen, & Pomberger, 2018b).…”

Guiding Future Research on the Valorisation of Shredder Fine Residues: A Review of Four Decades of Research

“…The assessment of research in material characteristics was performed on the premise that the purpose of material characterisation would be the subsequent development of upgrading and recovery processes. There, for a heterogeneous material such as fines, a comprehensive knowledge of the chemical and physical properties is crucial (Allegrini et al, 2014;Fiore et al, 2012;Hernández Parrodi et al, 2018a). The scope was assessed in regard to the sufficiency of properties and the level of detail in characterisation.…”

“…Given that the studies within this topic involve characterisation of selected chemical and physical properties for different types of fines (due to variations in input materials, shredding process, and particle size), a comprehensive understanding of both the resource and contamination potential is largely absent. As demonstrated by research on MSWI bottom ash (Dou et al, 2017;Lam et al, 2010;Margallo et al, 2015;Šyc et al, 2018), such comprehensive knowledge on the chemical and physical properties is essential for enabling effective development of resource recovery processes and facilitating the full valorisation of the material in question (Fiore et al, 2012;Hernández Parrodi et al, 2018a).…”

Assessing the Economic Potential of Landfill Mining: Review and Recommendations

“…The average of waste compositions from different landfills is used to represent continental (Van Vossen and Prent, 2011), national (Ford et al, 2013;Frändegård et al, 2015), and regional levels (Damigos et al, 2016;Danthurebandara et al, 2015b;Van Passel et al, 2013). Clearly, there is a large uncertainty to be accounted for, both within and among reported waste compositions (Hernandez Parrodi et al, 2018;Hogland et al, 2018;Hölzle, 2019).…”

“…The most recent concept of LFM even targets a zero-waste approach by including innovative resource recovery technologies, as well as extending the typical process chain (i.e. excavation, separation, and thermal treatment) with more downstream residue valorization processes (Danthurebandara et al, 2015a;Hernández Parrodi et al, 2018;Jones et al, 2013). Furthermore, the motivation for such projects has been suggested to go beyond traditional economic and environmental impacts by also considering revitalization of ecosystem services (e.g.…”